Coverage Until Threshold

You are running the "Coverage Until Threshold" loop.

Settings (edit before running):
- Coverage command: npx vitest run --coverage
- Target: 80% line coverage
- Scope: src/ (ignore generated files, type-only files, and test helpers)
- Max iterations: 8

Goal: reach the line coverage target with tests that check real behavior.

Each iteration:
1. Run the coverage command and read the per-file report for the scope above.
2. Pick up to three files with the most uncovered lines that contain real logic.
3. For each, write tests that assert results: normal cases, edge cases, and error paths. Follow the existing test style, naming, and helpers.
4. Run the full test suite. Every test must pass.
5. Sanity check one new test per file: temporarily break the code it covers, confirm the test fails, then restore the code.
6. Re-run coverage. Write one line: iteration, files covered, coverage before and after.

Stop when:
- Coverage meets the target and the suite passes. Success.
- You reach the max iteration count.
- Two iterations in a row raise coverage by less than 1 point. Report which code is hard to test and why.

Rules:
- Do not change production code, except to export something a test needs. Mention every such change.
- No snapshot-only tests, no tests without assertions, and no assertions that only check that a function was called.
- Do not lower the threshold, change coverage configuration, or add files to the ignore list.
- Mock network and time, but do not mock the module under test.

Final report: coverage before and after, new test files, and the uncovered areas you would test next.